--- coin/CMakeLists.txt.orig	2019-12-23 20:47:43.000000000 +0100
+++ coin/CMakeLists.txt	2020-11-30 21:32:23.759864515 +0100
@@ -591,6 +592,7 @@
     #include <GL/glx.h>
     int main() { (void)glXChooseVisual(0L, 0, 0L); glEnd(); return 0; }
   " HAVE_GLX)
+  list(APPEND COIN_TARGET_LINK_LIBRARIES X11)
 endif()
 
 # Checks specific OpenGL configurations